Alkyl sulfates



Patented July 15, 1952 [Siegfried Leonard "La G e-l e w a e NolDr-awingli rialNo. 5,186. 11- ;3 ..3 z

mveiitiea nzins I ondary sodium j alkylsulfates in; such a 1 manner that they" lose to low tem raturesj, .andjjtosoluticins rime sig said'sodium alkylsulfates mus; stabilized, f A

It is known that .by'sluliatior I I I II I i. e; olefinesfliaving at. least 6' carbon aton'ijs, e; g. from 8 to, 20 carbon atomslin the nioleculeor of the corresponding secondary alcohols; and new tralization oi .the resulting sulfation 'product sec ondary sodium I alkylsulf'ates can. be prepared; which possess very valuablejsurfacej-active' prop In "the prepara on J of we .so i y si d fates the latter are obtained in theform" of gages-.1 ous solutions which generally contain, besides for example20 t-2 5% of estersalta certain proportion of inorganicsalt; chiefly sodiumlsulfate, which may be'relativelyhigh, e. g. 6 to 7% or higher. These solutions showa tendency to gel and/ or crystallize after a short time, when stored,

especiallyat' l'owtemperaturesu-As a result con- I to crystallize and/orgel at low temperatures is checked considerably, as a result of which the said phenomena take a much longer time in appearing. This'eiiect is all the more surprising because the corresponding potassium alkyl sulphate solutions show a greater tendency to crystallize and/or gel than the sodium alkyl sulphate solutions.

Consequently, the process according to the invention is characterized by the addition of an inorganic potassium salt to the solution to be stabilized so as to cause the resence therein of a suincient quantity of potassium ions for the tendency of the solution to crystallize and/ or gel to be considerably checked even at low temperatures, e. g. between 0- and C.

The quantity of potassium ions required to atrelates :toa, process. for stabil tions of higher, j surf ace-active s ec'-' I, 'substantialI extent theirtendencyj .to crystallize and gel, jparticularly I at pplication January 29,-194s. se-*. 1.. the Netherlands'zEebruary I *STABILIZED'AQUEOUS SOLUTIONS 0F sUR-' z 1 FACE-ACTIVE; SODIUM SECONDARY I .-.;,ALKYL'SULFA'1ES "gedijk and Pieter Nicolaas f Degens, Amsterdam; Netherlands, assignors to 1 Shell'Development Company, San Francisco,

1 f D awa e;

tain-the-stabilization' aimed at 'is preferably intro- I duced by adding potassium sulphate to the sodium alkyl sulphate solution to be stabilized, it having I been found-that with this salt a particularly, efiective stabilization is attained. l- Iowever,. also the .additionofother, soluble, inqr anic. poms-f sium salts, such as the chloride andthe nitratef results in .a considerable improvement of] the stability. Ester salt solutions containing only a 'moderate proportion e. g. 2-5,% of sodium sulfate; I

as well as those containing a higher content, c. g. 64% or more, can be effectively stabilized according to the invention. I I I I 'Theguantty of the potassium ions required for attaininga sufficientidegreeoi stabilization de-" I ends" ifiheit eqe fixe't qn"an na f the secondary sqdium'alkyl sulphate'i'fsolutions, onth'e i content of inorganic saltf of said solutions, and further on the form in whichthe potassium ions are introduced; It isin general larger accordin 1y flas' the concentrationof' sodiumalkyl sulphates and inorganic salt is highen fI'he proper quantity to be employed may. be determined;experimentally for each individual case. Inigener'ala suflicient quantity of potassium'ions should bepresent tor the atomic ratio between potassium and sodium" to be about 1 3. As a rule, ratios substantially ex ceeding lzlshould beavoided, since in that case, especially the solutions have a comparatively. high content of estersalt, and inorganic salfiitjis not possible to obtain sufficiently stable products."

The presence of the potassium ions'is fou'ndto check not only the crystallization of the sodium sulphate usually present in the ester salt solution, but also the troublesome gelling tendency of the ester salt. 1

The effect attained by the process according to the invention i 'further illustrated by the follow- 1 ing'examples.

Example I An ester salt solution was prepared by reaction of a mixture of olefines containing from 10 to 18 carbon atoms in the molecule with sulfuric acid and neutralization of the resulting sulfation product with sodium hydroxide.

To the solution which contained 30% sodium alkyl sulphates and 0.5% sodium sulphate increasing amounts of potassium sulphate were added. The resulting solutions were kept at a temperature of 5 C. in a cooling-thermostat and the period of time till crystallization set in was determined.

The result of these tests is given in the follow- 

1. A SURFACE-ACTIVE COMPOSITION CONSISTING ESSENTIALLY OF AN AQUEOUS SOLUTION OF SODIUM SECONDARY ALKYL SULPHATE HAVING FROM 8 TO 20 CARBON ATOMS IN THE MOLECULE CONTAINING 20% TO 30% BY WEIGHT OF SODIUM ALKYL SULPHATE, FROM 2% TO AT LEAST 70% OF SODIUM SULPHATE AND SUCH A PROPORTION OF AN INORGANIC POTASSIUM SALT SELECTED FROM THE GROUP CONSISTING OF POTSSIUM SULFATE POTASSIUM CHLORIDE, AND POTASSIUM NITRATE THAT THE ATOMIC RATIO BETWEEN POTASSIUM AND TOTAL SODIUM IN THE SOLUTION RANGES BETWEEN ABOUT 0.3:1 AND 1:1. 